1. Field of the Invention
The invention relates generally to a cleaning apparatus for nozzles used in semiconductor processes and, more particularly, to a cleaning apparatus for photoresist dispensing nozzles, the cleaning apparatus having a cleaning solvent inlet that is positioned and configured to squirt the cleaning solvent directly onto the photoresist dispensing nozzles.
2. Description of the Related Art
Photoresist used during photolithography is dispensed onto semiconductor wafers using a plurality of nozzles. When these nozzles are not being used, they are returned to their home positions. The home positions of the nozzles correspond to their storage locations in a cleaning apparatus.
A conventional cleaning apparatus 10 in which the nozzles are stored is illustrated in FIG. 1 as an exploded view. The cleaning apparatus 10 includes a nozzle base 20, a thinner pot 30, a solvent bath or catch pan 40, and a drain 50. Each of these components has openings corresponding to four photoresist dispensing nozzles 11, 12, 13, 14.
In their home positions, the photoresist dispensing nozzles 11-14 are inserted into corresponding openings 21, 22, 23, 24 of the nozzle base 20. The tips of the nozzles, when inserted, extend into corresponding openings 31, 32, 33, 34 of the thinner pot 30, near the bottom of the thinner pot 30, as shown in FIG. 2, which shows a side cross-sectional view of the conventional cleaning apparatus 10.
While the nozzles are in their home position, photoresist that remains in the nozzles dries up and begins to clog them up, especially at the tip and when the nozzles sit idle for any length of time. When any one of such nozzles is used to dispense photoresist during the photolithography process, dried photoresist particles become dispensed onto the semiconductor wafer and leads to defects. In some cases, little or no photoresist is dispensed due to clogging.
Three different techniques have been used to combat this problem. First, maintenance technicians remove the nozzles and manually clean each nozzle with a photoresist cleaning solvent. Second, the nozzles undergo a dummy dispense procedure. In this procedure, the photoresist is dispensed through the nozzles while they are in their home positions. This procedure keeps the nozzle tips continuously wet in an effort to prevent the photoresist remaining at the nozzle tips from drying up. The dispensed photoresist is dumped through the drain 50. Third, photoresist cleaning solvent is introduced through an inlet 60. The cleaning solvent that is introduced floods the solvent catch pan 40 but does not come in contact with the nozzles. At best, the nozzles are moistened from the solvent vapors, but this is not sufficient to prevent the nozzle from clogging.
The invention provides a cleaning apparatus for photoresist dispensing nozzles which has one or more solvent needles positioned to oppose corresponding nozzle or nozzles that are stored in their home positions so that, as photoresist cleaning solvent is introduced through the needles, the photoresist cleaning solvent is squirted directly at the nozzles to clean the nozzles and keep them from clogging. The squirting of the photoresist cleaning solvent through the needles preferably occurs at a specified interval to prevent the photoresist remaining in the nozzles from drying up.
Additional objects, features and advantages of the invention will be set forth in the description of preferred embodiments which follows.